82 PLEIOCENEPOS.SILS. 



VENUS CONCENTRICA. — Gmel. 

 Plate XXI. Fig. 7.. 



Venus concentrica, Gmel, p. 3286, No. 82. 

 Artemis concentrica, Born., Sow. Gen., fig. 4. 



V. testa orbiculari, convexo-depressa, sub-cequilaterali; concentrice striata; striis confertis; 

 lunula minima, cor data. 



Description. Shell orbicular, convex, depressed, nearly equilateral; concentrically 

 striate; striee closely arranged; lunule small, cordate. 



, This species is remarkable for its orbicular outline, depressed form, and although the 

 concentric stride are very regular, there are portions of the disks raised concentrically. 

 The buccal margin is regularly rounded, the anal side somewhat straight, and occa- 

 sionally sub-truncate. In some varieties of the species, an obsolete, narrow, corrugated 

 fold extends from the umbones to the pallia! margin. The hinge plate is broad, and the 

 disposition of the teeth resembles that in the genus Lucina quite as much as in the genus 

 to which it is referred. 



We have carefully compared this with the recent form of the species so common along 

 the Southern coast, and can find no essential difference between them. The fossil varies 

 considerably, but a similar range of variation may be traced in the recent forms of the 

 shell. 



Plate XXI. Fig. 7, Natural size. 



Locality. Sumter District. . 



Museum, College of Charleston. 



